1. Field of the Invention
The present invention relates to a technique for protecting data saved in a wireless communication terminal, and particularly to a technique for protecting data depending on a range in which wireless communication can be established.
2. Description of the Background Art
A notebook personal computer, a portable phone, a PDA (Personal Digital Assistant), or another wireless communication terminal has a storage device of a large capacity and it is capable of saving document data, spreadsheet data or another file, simulation software, an electronic payment system, or other application programs. In addition, with improvement in portability, a location where a wireless communication terminal can be used is not limited to an office or a home but includes a public area where wireless communication can be established such as a station.
In order to connect a wireless communication terminal to a network for use, a parameter for allowing communication with the network should be set.
For example, Japanese Patent Laying-Open No. 2007-143117 discloses an invention for simplifying setting of a communication parameter without making a user aware of the communication parameter. In setting a communication parameter, a communication device according to this invention identifies a communication parameter setting wireless network based on a network identifier of its own. When a network identifier matching with the network identifier of the communication device can be identified, a communication parameter is set for a communication device within the wireless network. If identification of a network identifier fails, switching to manual setting of a communication parameter is made (see the Abstract).
Japanese Patent Laying-Open No. 2005-142848 discloses an invention relating to a wireless LAN (Local Area Network) system with improved security, reducing load on an authentication server and a network and authenticating a client connected to wireless LAN. According to this invention, an access point 3 stores authentication information for authenticating a client 2 in a cache memory and refers to the authentication information, and authenticates client 2 that has requested access to wireless LAN 5 on behalf of an authentication server 1. Therefore, the wireless LAN system in which transmission of security information between access point 3 and authentication server 1 is reduced and security is improved as well as load on authentication server 1 and network 4 is mitigated can be obtained (see the Abstract).
In addition, Japanese Patent Laying-Open No. 2004-266870 discloses an invention relating to a parameter setting system, in which a set of parameters necessary for connecting a personal computer to a connection target network through wireless LAN can automatically be set. According to this invention, an access point provided in the connection target network sends a beacon 13 including an SSID (Service Set Identification) code representing one parameter in that one set of parameters. A personal computer 20 includes an SSID extractor 14 receiving beacon 13 through wireless LAN and extracting the SSID code, a network connection information file 17 having that one set of parameters, a registry 19, and a parameter detector outputting that one set of parameters in network connection information file 17 as a detected parameter and writing the detected parameter in registry 19 as the set parameter when the SSID code received from SSID extractor 14 matches with one parameter in that one set of parameters in network connection information file 17 (see the Abstract).
Moreover, regarding the use of the wireless communication terminal, a user may leave the wireless communication terminal behind or the wireless communication terminal may be stolen. Therefore, security of the wireless communication terminal also gives rise to a problem.
Japanese Patent Laying-Open No. 2004-304344 discloses an invention capable of preventing leakage of confidential data even if a computer terminal is stolen. According to this invention, a computer terminal device 50 requests connection with a wireless LAN access point 30, transmits a request to wireless LAN access point 30, identifies a security zone by determining whether connection with wireless LAN access point 30 has been established or not and whether a received MAC (Media Access Control) address of wireless LAN access point 30 matches with a MAC address registered in advance or not, registers data requiring data security service in the security zone as registration data, restricts access to the registration data, and discards the registration data when computer terminal device 50 is identified as being outside the security zone, and a server device 10 transmits the MAC address of wireless LAN access point 30 in response to a request (see the Abstract).
According to the conventional techniques as described above, various types of setting (such as proxy, validity/invalidity of DHCP (Dynamic Host Configuration Protocol), an IP (Internet Protocol) address, or the like) of the network can be changed in accordance with an access point (SSID) of wireless LAN. In addition, according to the technique disclosed in Japanese Patent Laying-Open No. 2004-304344, in order to maintain security of data saved in the wireless communication terminal, a server device providing security service is required. Therefore, a configuration for maintaining security becomes complicated and security cannot be improved in a simplified manner.